The present invention relates generally to the field of preformed, light-weight concrete panels for forming walls, and additionally roofs, of buildings. More specifically, the present invention relates to a prefabricated panel composed of a concrete mixture containing polystyrene beads as an additive, with a specialized system of hardware for joining adjacent panels in a secure and stable manner to form an assembly of such panels to define a structure.
Concrete blocks and other prior art wall designs formed upright and incrementally generally have irregular faces and weak cohesion. The placing of concrete blocks is only as accurate as the skill of the block layer permits. The resulting exposed exterior face of the wall is always uneven to some extent, requiring a substantial covering of stucco or other type of finish. More important is that the mortar used to join the concrete blocks is below the strength of properly hardened concrete and forms a relatively weak bond with the blocks. Hurricanes and other natural disasters can sometimes shatter such walls. Finally, the insulating properties of such walls are at most inadequate.
Attempts have been made to solve these problems with a preformed wall. The panel of Walston, U.S. Pat. No. 4,512,126, issued on Apr. 23, 1985, for example, is formed of two layers of polystyrene fitted into a ribbed concrete shell in a multiple step, multiple pour process. Anchor hooks must be embedded in the floor slab when it is poured. Problems with Walston include time-consuming and expensive forming methods and awkwardness and complexity in anchoring procedures.
There have long been prefabricated wall panels for rapid construction of buildings. None teach panels combining high strength, maximum insulating properties, single pour formation, and solid, easy to use anchoring means.
Additional examples of prior panels include Lewis, U.S. Pat. No. 4,494,353, issued on Jan. 22, 1985. Lewis teaches a rigid, rectangular insulating member which fits within opposing vertical hat channels and a bottom channel. The bottom channel is welded to a bottom plate which is secured by anchor bolts to a concrete foundation. Panel connector strips are welded to the hat channels and reinforcing rods extend through holes in the connector strips. Gunite is then sprayed over this structure to form the finished panel. Numerous and complicated metal parts make Lewis expensive. Also, two separate layers of concrete are required, adding pouring and curing time and expense.
Kinard, U.S. Pat. No. 4,532,745, issued on Aug. 6, 1985, discloses a wall formed of foam blocks and channels. The blocks, which have periodic vertical bores, are placed edge to edge. Then a channel with periodic holes is placed along the common top edge of the blocks so that the holes align with the vertical bores. Concrete is poured through the holes into the vertical bores, filling the bores and the channel, and hardens to form a solid skeletal structure. Kinard does not provide a strong external surface suitable for an outside wall.
Dunker, U.S. Pat. No. 4,624,089, issued on Nov. 25, 1986 is an anchor in the form of a plate having holes through which reinforcing rods extend, for holding reinforced sandwich panels together. An end of the anchor also wraps around a perpendicular mesh rod. Concrete is poured to form a carrier panel such that the end of several such anchors protrude therefrom. Then a layer of insulating material is fitted against the panel so that the protruding ends of the anchors punch through the insulating layer. Then rods for the mesh are fitted through holes in the anchor protruding ends and another concrete layer is poured around the mesh and the anchor ends. Only the outside wall of most buildings need to be this strong, so that Dunker is wasteful of materials and needlessly expensive.
Marks, U.S. Pat. No. 4,974,381, issued on Dec. 4, 1990, describes another anchor member for joining the outer slab of a sandwich panel. A metal slat has a hole in each end for receiving a reinforcing rod of each slab, and the slat extends through the middle insulating layer. This anchor is not intended to anchor the panel to a foundation, but is instead part of the internal panel structure. Marks, like Dunker, is another wasteful sandwich arrangement.
Porter, U.S. Pat. No. 4,947,600, issued on Aug. 14, 1990, teaches an interface for mounting a brick wall covering on an existing concrete wall or slab. One side of an angled member is attached to slab to form a shelf, additionally secured by a bracket. Studs extend through and join a foam layer to the slab. Mesh is placed over the foam layer and brick is laid on the shelf in front of the foam. Porter does not teach an effective, economical approach to constructing a new, insulated wall.
Huettemann, U.S. Pat. No. 4,841,702, issued on Jun. 27, 1989, discloses a three-layer panel. The middle panel is an insulating slab such as polystyrene foam. A sheet of particle board is joined to one side and grooves are cut into the other side of the foam slab. Concrete is poured over the grooved side so that the concrete fills the grooves and creates structural ribs. Pouring continues until a layer of concrete is formed on top of the foam slab. Reinforcing rods may be placed in the grooves to strengthen the ribs. No efficient anchoring or lateral connection means are provided.
Zimmerman, U.S. Pat. No. 4,751,803, issued on Jun. 21, 1988, describes a multi-layer insulating panel having pre-formed concrete ribs. The ribs, referred to as studs, have metal connecting members protruding from one edge. The ribs are placed in parallel relationship in a jig with the connecting members protruding upwards. Additional ribs are formed to create a border around the inside of the jig. A layer of insulating material is placed on top of the ribs and the protruding members pierce through the insulation material. Wire mesh is laid over the insulating material and concrete is poured on top of the mesh. The concrete hardens around the connecting members but does not form a true unitary structure.
Sanger, U.S. Pat. No 5,313,753, issued on May 24, 1994, describes a panel consisting of a layer of concrete with a certain thickness, to which is appended a board of polystyrene foam. A steel stud is inserted vertically in the foam board every 16 in. The concept involved in that invention provides for a sturdy panel with high insulation. Conversely, the use of regular concrete versus the special insulated concrete mix used in the present invention makes for a substantially heavier panel which does not have the flexibility and versatility of the panel obtained with the present invention and requires a more labor intensive process.
It is thus an object of the present invention to provide a prefabricated panel having a simple design which is inexpensive to construct.
It is another object of the present invention to provide a prefabricated panel which has an exterior face of high strength and has superior insulating properties.
It is still another object of the present invention to provide such a prefabricated panel that is simple to pour and permits rapid fabrication.
It is also an object of the present invention to provide such a prefabricated panel which has easy anchoring and interlocking means for rapid and strong assembly.
It is finally an object of the present invention to construct such panels of a special insulated concrete mix which, while it retains the structural qualities demanded by engineering design, additionally provides high insulation properties in and of itself, and lends itself to performance not otherwise available with regular concrete.